1. Field of the Invention
The present invention relates to a silver halide photographic light-sensitive member with at least one backing layer containing dyes.
2. Description of the Prior Art
Where a silver halide photographic light-sensitive member has a photographic emulsion layer on one side of a support thereof, a layer called a backing layer on the other side of the support is sometimes employed. This backing layer is provided for the purpose of preventing halation, being able to distinguish the face of the light-sensitive member in a safety light, preventing light fog, preventing curling, preventing charging, and the like. Where the prevention of halation, ability to distinguish the face, or prevention of light fog is intended, the backing layer is colored (including black-coloration) using dyes or pigments so that it absorbs light sufficiently in the wavelength region to be absorbed.
The thus-colored backing layer must be removed or decolored in the course of photographic processing in a manner which does not effect adversely the photographic image formed at the photographic processing. Except for the case where the backing layer must remain after the end of the photographic processing for the purpose of preventing curling, and the like, it is rather desirable for the backing layer to be removed in the course of photographic processsing after exposure, for instance, in the course of developing by the use of an alkaline developer. This is because the surface of the backing layer is damaged and the backing layer tends to interfere with the photographic image. Where the backing layer is removed from the light-sensitive member during photographic processing, it is desirable for the dye or pigment used in coloring the backing layer to be decolored in a photographic processing solution and not contaminate the photographic processing solution. For example, where the backing layer is soluble in the alkaline developer, the dye or pigment preferably is decolored in the developer.
Hitherto, in coloring the backing layer, pigments such as carbon black, manganese dioxide, and the like, or dyes such as a triphenylmethane and the like have been used. The use of compounds, which are soluble in low boiling organic solvents such as alcohols and the like, in the backing layer is advantageous from the standpoint of commercial production in that coating solutions using such organic solvents as a solvent can be used and the drying of coated layers is easy. Thus these methods have been used for a long time. Alcohols such as methanol and ethanol, ketones such as acetone and methyl ethyl ketone, esters such as methyl acetate and the like, etc., can be used as the solvent. Of these solvents, alcohols such as methanol, ethanol, and the like are most generally used because they are easily handled. In this case, dyes which are soluble in the alcohols are used.
Known alcohol-soluble dyes for the backing layer include oxonol dyes containing a pyrazolone nucleus, styryl dyes containing an indole nucleus, and the like as well as triphenylmethane dyes or diphenylmethane dyes. A number of triphenylmethane dyes for this purpose are known, and examples include those dyes as described in, for example, Japanese Pat. Nos. 3,141/1938, 3,083/1953; British Pat. Nos. 294,104, 373,004, 446,583, 790,023, 1,025,567; West German Pat. Nos. 1,038,395, 1,447,792; Belgian Pat. Nos. 632,536, 661,585; U.S. Pat. Nos. 1,912,792, 2,147,112, 2,150,695, 3,018,177, 3,382,074, etc. Known oxonol dyes for this purpose are those dyes as described in, for example, Example 1 of British Pat. No. 506,385 and Japanese Pat. No. 18,439/1966. Known styryl dyes for this purpose are those dyes as described in, for example, Japanese Pat. No. 5,920/1956; and U.S. Pat. Nos. 1,845,404 and 3,652,283.
Of these dyes, triphenylmethane dyes are comparatively preferred as the dye for the backing layer because they have a relatively high absorption density, they are readily decolored in an alkaline developer containing a sulfite, and the like. However, where these dyes are contacted with the photographic emulsion layer for a long period of time, that is, the backing layer containing these dyes or fragments thereof is contacted with the photographic emulsion layer for a long period of time, a slight desensitization often results. Since Fuchsine and imine structures contained in triphenylmethane dyes are harmful to the human body, for example, carcinogenic, mass production of these dyes or their starting materials are not desired.
Oxonol dyes have little tendency to cause desensitization and fog even when contacted with the photographic emulsion layer and are harmless to living things. However, since their absorption densities are low, they are disadvantageous in preventing halation and light fog. Furthermore, where the light-sensitive member is subjected to supersonic cleaning in a cleaning solution comprising chlorinated lower hydrocarbons prior to exposure, alcohol-soluble oxonol dyes are inadequate in that they dissolve in the cleaning solution and cause the cleaning solution to become colored. In a light-sensitive member for recording and reproducing a minute image, for instance, a light-sensitive member for producing a photomask as used in the course of producing an integrated circuit element, the presence of dust provides a significant defect in the image, and thus it is necessary to remove dust using the above supersonic cleaning. In this supersonic cleaning, the most generally used cleaning solution is 1,1,1-trichloroethane. If dyes dissolve in the cleaning solution during supersonic cleaning, the cleaning solution is gradually colored and ultimately the emulsion layer of the light-sensitive member is colored.
The hitherto known styryl dyes have good absorbance, good photographic chemical effect on a photographic emulsion and freedom from biological hazards. However, most are soluble in chlorinated hydrocarbons and are insufficiently decolored in an alkaline developer containing a sulfite. Thus, these dyes color the developer, particularly after the developer has been used in processing a large number of light-sensitive members. Dyes having a sulfoalkyl group as a substituent on a nitrogen atom of an indolenine nucleus as described in U.S. Pat. No. 3,384,487 are insoluble in chlorinated lower hydrocarbons, but insufficiently soluble in alcohols, and thus it is difficult to produce a backing layer having a sufficient absorption density using these dyes.